Means of and apparatus for transmitting messages through submarine and other like cables



' 1 631254 June 7, 1927. W. ESTAUGH MEANS OF AND APPARATUS FOR TRANSMITTING MESSAGES THROUGH SUBMARINE AND OTHER LIKE CABLES Filed Avril 1925 A TORNEYS Patented June 7, 1927.

UNITED. STATES 1,631,254 PATENT oFFicE.

wILLIAMnsTAUeH, or WANSTEAD, ENGLAND.

MEAN$ (Q1? AND APPARATUS FOR'TRANSMITTING MESSAGES AND OTHER LIKE CABLES.

THROUGH SUBMARINE Application filed. April 8, 1925, Serial No. 21,676, and in Great Britain April 16, 1924.

This invention relates to the construction of cables and the arrangement of apparatus for transmitting messages through them and has for its objectin'iprovements whereby retardation due to electrostatic capacity is minimized or avoided. These improvements consist in providing a concentric cable having an outer insulated conductor electrically charged by an cart-lied source so as to form a screen that completely envelopes an inner insulated conductor whose electrostatic capacity controlled by the potential of the charge carried by the said outer conductor and is determined by the difference between that charge and the charge on the outer surface of the dielectric surrounding the said. outer conductor, and in providing transmitting and receiving apparatus arranged and connected thereto as hereinafter described. It the receiving ends of both the inner and outer conductois are connected tothe' positive tern'iiual of an earthed source the potential at that end will be the same as'the charging source but there will be gradual fall of potential in the outer conductor towards the receiving end due to leakage and resistance. In order to obtain a suitable fall of potential at the sending end of the outer conductor it may it'necessary be earthed. at that end through a suitable resistance.

The capacity of the inner conductor will under the foregoing conditions be determined by the negative potential on the outer surface of the cable except in so far as it is screened by the positive charge carried by the outer insulated conductor.

It now the inner conductor be electrically charged at the transmitting end by an earthed source to a suitable higher potential than the outer conductor. the capacity of the inner conductor will be increased while the higher potential is applied and the superimposed charge will be bound to it by the corresponding higher negative charge on the outside of the cable, but directly the charging source at the sending end. is disconnected the superimposed. charge will be free and will be discharged from it at the receiving end where the said charge can be caused to actuate a suitable receiver which may be ac tuated by current or potential.

In order to obtain these results the resistance of the inner and outer conductors and the thickness, specific inductive capacity and dielectric resistance of the insulating material separating and surrounding the said conductors must be suitably proportioned and; accurately adjusted to obtain satisfactory working.

The inner conductor of the cable employed may or may not be stranded and is surrounded by and insulated from the outer conductor which maybe in the form of a. tube composed of helica ly applied tape or stra ded wires of copper or other suitable material surrounded by suitable insulating material and the usual mechanical proteotion.

I will now proceed to more particularly describe my invention with the aid of the accompanying drawings, in which- Fig. 1 is a diagram showing the improved cable and transmitting and receiving apparatus constructed and arranged according to one mode'of carrying out the present in vention and Fig. 2 is a transverse section through the cable on the line 2 2 in Fig. l.

The cable C consists of an inner conductor a and an outer conductor 7). separated from each other by insulation. 0 andsurrounded by an outer layer of insulation (Z and the usual mechanical protection (not shown).

Accordingto the mode of carrying out the invention shown in the drawings the outer conductor ,7) and inner conductor aare connected to the positive pole of an earthed battery f at the receiving station B through a potentiometer g to enable the potential applied to be adjusted.

iVith this arrangement both conductors a and .7) will be constantly charged but the ca pacity of the outer conductor Z) will be greater than the inner conductor a owing to the screening effected by the said outer conductor. This screening however is not so eliectual at the transmitting end owing to the fall of potential in the outer conductor Z) due to resistance and leakage so that the capacity ofthe inner conductor will. be oorrespondingly greater at the transmitting end.

The inner conductor a is also connected at its transmitting-end to the positive pole ot' an earthed battery 71, of higher potential through a signalling key i and a potentiometer 7' to enable the E. M. F. applied to be adjusted.

lVhen the signalling circuit is closed at the transmitting station T by operating the key 5 the capacity of the inner conductor is increased by the higher potential applied and the incomplete screening of the outer eonductor b but is immediately charged by the signalling current which is bound by the negative potential applied to the earth. S soon as the signalling circuit is broken by releasing the key 1' the superimposed charge is freed and is discharged through the re ceiving instrument 7c at the distant end of the line.

To enable the potential 01 the outer condoctor .72 at both ends to be ascertained an electrostatic voltmeter Z is connected to it at the receiving end and a similar voltmeter m is connected to it at the transmitting end.

Another electrostatic voltmeter n is connected to the transmitting circuit to enable the potential of the signalling current to be accurately adjusted by the potentiometer j with relation to the potential of the outer conductor at the transmitting end as shown by the voltmeter m I claim:

} 1. Method of transmitting electric impulses through a cable consistinr in surrounding an inner insulated signal conductor with an outer insulated conductor both of which are connected to the same pole of an earthed charging source at the receiving end and connecting the transmitting and of the inner conductor to the pole of the same sign of an earthed signalling source of higher potential. through a key so that the excess charge will be discharged through a receiver located between the end of the inner conductor and the charging source at the receiving end when the signalling source is disconnected, substantially as set forth.

2. Means and apparatus for transmitting messages through submarine and other like cables, comprising a cable having an insulated inner conductor, an insulated outer conductor, a. receiving instrument connected to the receiving end of the said inner conductor, an earthed electrical charging source connected to the other terminal of said receiver and to the adjacent end of said outer conductor, an earthed signalling source of higher potential connected to the inner conductor at the transmitting end and a key to control the signalling current substantially as set forth.

3. Means and apparatus for transmitting messages through submarine and other like cables comprising a cable having an insulated inner conductor, an insulated outer tmnd-luctor a receiving instrument connected to the receiving end of the said inner conductor, an earthed electrical charging source connected to the other terminal of said receiver and to the adjacent end of the said outer conductor, an earthed signalling source of higher potential connected to the inner conductor at the transmitting end, means oi measuring the potential at both ends of the outer conductor and at the transmitting end of the inner conductor, means of adjusting the potential of the charging source at the receiving end, means of adjusting the potential of the signalling source at the transmitting end and a key to control the signalling current substantially as set forth.

In testimony whereof, I have signed my name to this specification at 61 and 62 Cl1EL11- cery Lane, London, England, this27t=h day of March, 1925.

lVILLIAM ESTAUGH. 

